Somaclonal variation is a well known
phenomenon in plants regenerated from tissue cultures (6). In pea,
cytological variation was reported both in undifferentiated cultures and
regenerated plants (4, 8, 9, 11). Morphological and physiological
variation was observed in plants regenerated from long-term callus
cultures (2,5).

Immature primary scales and leaflets
from 3-4 day-old seedlings of the cv. Century were cultured basically
according to the procedure of Mroginski and Kartha (7), with modifications
in some experiments. Regenerated shoots were rooted (3) and successively
transferred to a greenhouse. On the whole it was possible to analyze the
progenies of 24 R1 plants.

In 18 R2 families no
variation was observed. R1 plants were regenerated after 3
months of culture and the results agree with those reported by Rubluo et
al. (10). The other 6 R1 plants were regenerated from
cultures grown in vitro for three months
on a MS medium with NAA and BAP at 10 mkm each, subcultured for two months
on the same basal medium with the NAA level reduced to 0.1 mkm, and
finally transferred for a further 45 days on a basal medium without growth
regulators. Three out of these 6 plants segregated for chlorophyll and
morphological mutations (Table 1). One of them appeared as a
chlorina-type mutation, another had funnel-shaped and laciniate
leaflets resembling the lac mutant described by Blixt (1), while a
third one showed an increased number of basal branches and reduced plant
growth and leaflet size. From the first two segregation ratios a monogenic
recessive mutation can be hypothesized, whereas in the third case a deficit of recessives was observed.
Work is in progress to better characterize the genetic basis of the mutations
observed.